"""
160. Intersection of Two Linked Lists (Easy)
Write a program to find the node at which the intersection of two singly linked lists begins.

For example, the following two linked lists:
begin to intersect at node c1.

Example 1:
Input: intersectVal = 8, listA = [4,1,8,4,5], listB = [5,0,1,8,4,5], skipA = 2, skipB = 3
Output: Reference of the node with value = 8
Input Explanation: The intersected node's value is 8
(note that this must not be 0 if the two lists intersect).
From the head of A, it reads as [4,1,8,4,5]. From the head of B,
it reads as [5,0,1,8,4,5].
There are 2 nodes before the intersected node in A;
There are 3 nodes before the intersected node in B.

"""


# Definition for singly-linked list.
class ListNode:
    def __init__(self, x):
        self.val = x
        self.next = None


class Solution(object):
    def getIntersectionNode(self, headA, headB):
        ha, hb = headA, headB
        while ha != hb:
            ha = ha.next if ha else headB
            hb = hb.next if hb else headA
        return ha


